Ensure we actually use a 20m timeout as the default
Ensure we actually use a 20m timeout as the default

I also slightly re-organized how the default was set, so it will always
rely on the status of the $timeout variable and also the final variable
name matches the name of the Packer option.

elasticdog/packer-arch,aidanharris/packer-arch,tomaspapan/packer-arch,appleby/Lisp-In-Small-Pieces-VM,cosmo0920/packer-arch,tomswartz07/packer-arch,slash170/packer-arch,agt-the-walker/packer-arch,dragon788/packer-arch